[Proposal] Allow to use evaluation_interval for alert FOR calculation

[dmajere]

Allow to use evaluation_interval for alert FOR calculation

It's a common problem to find a right value for alerts FOR parameter.
In general you want your alert rule to be evaluated for N evaluation periods, so you have to manually calculate FOR: N * evaluation_interval, which is error prone due to possible changes of a prometheus server that would lead to necessity to change [possibly] every alert rule configuration.
It would be great to have an ability to specify evaluation_interval based evaluation as a value for FOR.
For example:

 - alert: AlertName
    expr: job:metric > 0.1
    for: 5 * config:evaluation_interval
    annotations:
      summary: my alert rule

[beorn7]

Does #4277 help with this?
Also, see #1154.

[dmajere]

No, not really, proposal is not about alert rule testing, but about making FOR dependency on evaluation_interval more explicit. So, it would be easier to maintain alert rules after they are tested.

[simonpasquier]

This is more a job for your configuration management system which Prometheus doesn't attempt to replicate.